North Korean media Saturday hailed the youngest son of late leader Kim Jong-Il as "supreme commander" of the powerful military, in the latest sign that the untested successor is cementing his hold on power, AFP reports.

"We will uphold Comrade Kim Jong-Un as our supreme commander and general and we will bring the Songun (military-first) revolution to a completion," the ruling communist party's Rodong Sinmun said in an editorial.

It is the first time that one of the North's mouthpieces has used the title supreme commander -- a post previously held by his father -- for the new leader, already a four-star general though still in his late 20s.

"This shows that Jong-Un now has a firm grip on the military and the North is heralding this to the outside world," professor Kim Yong-Hyun of Dongguk University in Seoul told AFP.

"It also suggests that the North will continue with its Songun policy at least in the foreseeable future."

North Korea on Monday described the untested Jong-Un as the "great successor" after announcing the death of his father at age 69.

The latest acclamation is particularly significant because it came on the 20th anniversary of the declaration of Kim Jong-Il as supreme commander, said professor Yang Moo-Jin at Seoul's University of North Korean Studies.

"The editorial is aimed at preparing the people for Jong-Un becoming the supreme commander of the military and also announcing it to the outside world," he told AFP.

"Legal and official steps will follow sooner or later for his takeover from his deceased father as the supreme commander."

The latest dynastic ruler remains a figure of mystery to the outside world, which is seeking clues to future policy in the nuclear-armed nation.

Analysts expect little political upheaval following the death -- at least for now -- since regime members have an interest in preserving the status quo.

The son was appointed to senior military and party posts in September 2010, paving the way for a third-generation hereditary succession after the late Kim succeeded his own father Kim Il-Sung in the 1990s.

The country's regular armed forces total 1.19 million and the regime has a policy prioritising the military's needs over those of civilians.

Kim Jong-Un issued his first military order just before his father's death was announced Monday in what was seen as an indication that he already controls the armed forces, South Korean media reported on Wednesday.

In its editorial, the Rodong Sinmun urged Jong-Un to "heed the call from the people to you as the supreme commander and lead Kim Il-Sung's Korea to an eternal victory."